Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 221948

National Weather Service Sioux Falls SD
248 PM CDT Sun May 22 2022

.SHORT TERM...(This Evening through Monday)
Issued at 247 PM CDT Sun May 22 2022

Mid afternoon satellite images show a weak boundary is moving
through from the south, introducing slightly drier air near the sfc.
 This should allow sprinkles and showers to taper off late this
afternoon and cumulus to decrease in coverage. Cumulus dissipate
this evening for a period of mostly clear skies, but cirrus will
spread in overnight from the southwest. Strong sfc high pressure to
our east will keep winds light overnight with dry low level air
lingering through at least early Monday morning. Model guidance has
trended colder tonight due to decreased cloudiness this evening, so
bumped overnight low temperatures down into the upper 30s to lower
40s, but will need to monitor cloud cover.

Cool, cloudy spring like weather continues on Monday as a
progressive mid level wave tracks east into the Central Plains.
Initially will just see cloudiness increase early Monday, continuing
our below normal temperatures. Expect temperatures to peak in the
mid 50s to mid 60s with a south wind gusting into the 20s, warmest
near and east of I-29.

The better forcing for showers spreads into south central SD and
gradually eastward through the morning and early afternoon. 12z runs
have slowed down the main shower activity, confining higher rainfall
amounts to south central SD, but could still see instability-induced
showers out ahead near and west of I-29 especially during the
afternoon. Will likely see isolated thunderstorms embedded within
this activity but severe weather is not expected with weak 0-6km
shear and MUCAPE values mainly < 250 J/kg. Rainfall amounts through
Monday night will be fairly low with showers. Still expect areas
east of I-29 to see less than a tenth inch of rainfall. West of I-
29, up to a quarter inch is possible but much more likely west of
the James River than further east.

.LONG TERM...(Monday Night through Sunday)
Issued at 247 PM CDT Sun May 22 2022

On Tuesday, stronger broad scale troughing digs in upstream with
convection developing in the Southern Plains. This cuts off some of
our moisture supply and forcing as our initial shortwave departs.
Expect cloudy and cool conditions to continue Tuesday with spotty
showers possible through the day. Still think drier easterly winds
will make for more dry than wet hours during the day.

Rain chances really ramp up again heading into Tuesday night and
Wednesday, especially for northwest IA and northeast NE, as a
stronger shortwave lifts north into the Central Plains. The bulk of
the rain is favored to occur across central IA/MO, but areas near
and east of I-29 still have potential to be clipped Tuesday night.
As the mid level wave lifts north, rain chances increase across the
region heading into Wednesday morning. Rainfall amounts still look
quite light with mainly showers and little if any instability to
support thunderstorm development.

High confidence in Tuesday and Wednesday remaining cool and spring
like with daytime high temperatures in the 50s and 60s. Despite
overnight lows in the 40s, cloudiness should minimize threat of
frost development.

Much warmer weather returns for Thursday and Friday as drier air and
strong upper ridging build into the Central U.S. Over the weekend,
rain chances return. Though rain chances are likely overdone and
would not last all weekend as suggested by the latest NBM,
confidence in timing the approaching Pacific NW wave and perhaps a
secondary late weekend wave is too low to have any confidence in
details at this range.


.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1233 PM CDT Sun May 22 2022

VFR conditions will prevail through the period. Low VFR cumulus
at 4-8kft and occasional rain showers will linger through late
afternoon, dissipating this evening. West or northwest winds this
afternoon may gust up to 20 kts and will weaken to become light
and variable overnight. Winds turn southeasterly by morning with
cirrus building in overnight ahead of the approaching weather




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